The present invention relates generally to a focal plane shutter for a camera, and more particularly to a focal plane shutter capable of carrying out electric automatic exposure control and mechanical manual exposure control.
Before the advent of a focal plane shutter capable of carrying out electric automatic exposure control, as disclosed in Japanese Utility Model Laid-Open No. 70533/1979 and the like, exposure control was carried out mechanically by using a governor, gears, levers, springs and the like. After electric automatic exposure control was developed, by switching on a power source such as a battery in a camera, a member of the camera such as a shutter could be driven by using a motor or an electromagnet utilizing power from the battery.
A focal plane shutter capable of carrying out electric automatic exposure control enables a photographing operation by a single-lens reflex camera achieving high function in an extremely simple and convenient manner by electrically driving a motor or an electromagnet and therefore, at present, the focal plane shutter is adopted in almost all of single-lens reflex cameras. However, when the battery is consumed, the focal plane shutter becomes inoperable and therefore, when taking the camera on a photographing trip over a long period of time, spare batteries are needed, which is inconvenient.
On the other hand, in the case of a focal plane shutter capable of carrying out mechanical manual exposure control, it is not necessary to take consumption of the battery into consideration, and such a focal plane shutter is used easily by some users. However, some degree of skill and experience is needed in operating such a focal plane shutter and accordingly, it is inconvenient for a person who is not accustomed to use such a camera.
An object of the present invention is to provide a focal plane shutter which overcomes the aforesaid drawbacks and which enables either mechanical manual exposure control or electric automatic exposure control to be selected as needed.
According to an aspect of the present invention, there is provided a focal plane shutter comprising an exposure time period control mechanism for controlling an exposure time period by successively operating an opening member and a closing member, a selecting member for selecting an automatic exposure position and a plurality of exposure time period positions, a switching member operated by the selecting member for switching the exposure time period control mechanism in correspondence with a desired one of the exposure time period positions, and electromagnetic driving means for electrically driving the switching member, wherein when the selecting member is disposed at the automatic exposure position, the switching member is driven by the electromagnetic driving means and when the selecting member is disposed at the exposure time period positions, the switching member is driven by the selecting member.